PROJECT SUMMARY The Adult Changes in Thought (ACT) study's second Specific Aim focuses on cognitive resilience; Aim 2c focuses on synaptic changes as a possible resilience mechanism. This Supplement evaluates related hypotheses regarding astrogliosis, inflammation, and synaptic toxicity by incorporating technological advances in Histelide (Histology and ELISA on a glass slide) that enable multiplexed assessment. The investigators will test the hypothesis that for a given level of amyloid beta (A?) and tau, astrogliosis (measured with GFAP), neuroinflammation (measured with Iba1), and synaptic degeneration (measured with synaptophysin) will be lower in people who are resilient to the neuropathological changes of Alzheimer's disease.